This invention relates to enclosures for growing plants and more particularly to a portable self-contained greenhouse. Various structures are available presently for the purpose of growing plants in them. These plants often require relatively high moisture content in the atmosphere and the soil as well as relatively warm temperatures. Small portable greenhouses of the prior art include U.S. Pat. Nos. 4,051,626 to Richard L. Trumley; 3,121,975 to Eugene E. Duhamel, 3,106,801 to Gerald H. Risacher, 3,606,697 to Douglas H. Eden. Neither Trumley, Duhamel, Risacher nor Eden provide a vent regulator, flanged trays or a corrugated base for water distribution and tray support as does the present invention.